kingdom animalia subkingdom eumetazoa bilateria phyla … 3a/bio... · 2016-08-26 · •some had...
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Kingdom Animalia Subkingdom Eumetazoa
Bilateria Phyla Hemichordata & Chordata
Professor Andrea Garrison Biology 3A
Illustrations ©2014 Cengage Learning unless otherwise noted
Text ©Andrea Garrison 2014
Phylum Hemichordata
• Acorns worms (hemi = half; chorda refers to chordates)
• Marine • Sedentary
– Live in U-shaped tubes in sand or mud
• Muscular proboscis • Collar • Elongated trunk • Coelomate • Deuterostomes
2 Hemichordata and Chordata
Phylum Hemichordata
• Share some of the chordate traits – Pharyngeal gill slits
• Trait of chordates • Cilia create water flow in mouth
and out through gill slits – Suspended particles caught
for food – Respiration
– Dorsal nerve cord • Also have reduced ventral
nerve cord
– Rudimentary structure similar to notochord
• DNA evidence indicates more closely related to echinoderms
3 Hemichordata and Chordata
Phylum Chordata
• Coelomate
• Deuterstomes
• Share common chordate characteristics at some point in their life – Notochord
– Postanal tail
– Dorsal hollow nerve cord • Dorsal to notochord
– Pharyngeal gill slits
– Segmented muscles in body wall
4 Hemichordata and Chordata
Phylum Chordata
• 3 subphyla
– Invertebrate chordates
• Lack vertebrae
• Small, marine suspension feeders – Use pharyngeal gill slits for feeding and respiration
• Subphylum Cephalochordata
• Subphylum Urochordata
– Vertebrate chordates
• Subphylum Vertebrata
5 Hemichordata and Chordata
Subphylum Cephalochordata
• Lancelets (28 species)
• Chordate characteristics as adults
• Warm, shallow marine waters
• Sedentary
– Burrow into sand
– Filter feeders
6 Hemichordata and Chordata
Suphylum Urochordata
• Tunicates (Oura = tail); aka sea squirts
• Chordate characteristics as free-swimming larvae – Lose nerve cord, most of
notochord and tail in adults • Pharynx with gill slits
remains
• Larvae settle and metamorphose into sessile filter-feeding adults
Hemichordata and Chordata 7
Suphylum Urochordata
Hemichordata and Chordata 8
Subphylum Vertebrata
• All common chordate characteristics present at some point during life – Fish keep them throughout life
• Possess endoskeleton (usually bone) – Cranium (well-developed cephalization)
– “Notochord” broken into vertebrae • Protects nerve cord
• Possess neural crest
• Large, well-developed brain
Hemichordata and Chordata 9
Subphylum Vertebrata
• Skeletal structure – Axial skeleton
• Vertebral column – Vertebrae protect nerve
cord
• Cranium – Protects brain
– Appendicular skeleton • Girdles and appendages
w/joints • Anterior pectoral girdle
– Attach bones of forelimbs to axial skeleton
• Posterior pelvic girdle – Attaches bones of hind
limbs to axial skeleton
Hemichordata and Chordata 10
Subphylum Vertebrata
• Neural crest – Tissue from ectoderm
• Has been called 4th germ layer because of its importance
– Develop next to early nervous system
– Later cells scatter throughout body
• Large brain with 3 regions – Forebrain – Midbrain – Hindbrain
Hemichordata and Chordata 11
Subphylum Vertebrata
• As we study the vertebrate classes, we see development of derived traits – Variety in body form and function
• Evolutionists hypothesize these changes due to mutations in homeotic genes – control rate of development of certain body part(s) – Influence size and location of body part(s) – Hox gene complex felt to play a large role in
vertebrate evolution • More advanced vertebrates have more copies of the
complex
Hemichordata and Chordata 12
Hox Genes & Vertebrate Evolution
Hemichordata and Chordata 13
Vertebrate Phylogeny
Hemichordata and Chordata 14
Early Vertebrates (Now Extinct)
• Agnatha (a = without; gnath = jaw)
– Lacked jaws • Some had hook-like teeth
– Cartilaginous or bony skeleton
– Conodonts soft-bodied
– Ostracoderms heavily armored • Sucked mud into mouth
Hemichordata and Chordata 15
Early Vertebrates (Now Extinct)
• Gnathostomata (gnath = jaw; stom = mouth)
– Jaws • Upper jaw fixed in place
• Mouth inflexible
– Spiny shark related to extant bony fishes
Hemichordata and Chordata 16
Extant Vertebrate Groups
• Not all Agnatha and Gnathostomata are extinct • Superclass Agnatha—hagfishes and lampreys • Superclass Gnathostomata—jawed vertebrates
– Class Chondrichthyes—sharks, rays – Class Osteichthyes—bony fish – Tetrapods
• Class Amphibia—frogs, toads, salamanders • Class Reptilia—lizards, snakes, turtles, crocodilians • Class Aves—birds • Class Mammalia—mammals
Hemichordata and Chordata 17
Typical Vertebrate Organ Systems • Other vertebrate characteristics
– Large coelom • Organs held in place with mesenteries
– Well-developed muscles – Closed circulatory system
• #heart chambers related to ectothermy or endothermy
– Well-developed digestive system – Well-developed respiratory system
• Gills if aquatic • Lungs if terrestrial
– Well-developed excretory system • Kidneys • Ammonia, uric acid or urea
– Well-developed reproductive system • Dioecious • Egg development
– Oviparous – lay eggs – Ovoviviparous – embryo with large yolk, develop in oviduct, young born live – Viviparous – young nourished by mother via “placenta”, born live
• As we go through vertebrate groups, we’ll see adaptations in these systems
Hemichordata and Chordata 18
Superclass Agnatha
• Lack jaws, scales • Cartilaginous skeleton • Hagfishes
– Release lots of mucus
• Lampreys – Ectoparasites
• Cylindrical body • Branchial pouches
– Gill filaments attached to walls of pouch
• No paired fins (lack stability in water) • 2-chambered heart
– Ectothermic • low O2 needs
• Excrete ammonia – Immediately diluted in water
• Oviparous – Large larvae
• 3-7 yrs as larvae in freshwater
– Hagfish possess both sex systems initially, but only one matures
Hemichordata and Chordata 19
Superclass Gnathostomata Class Chondrichthyes
• Sharks, rays (khondros = cartilage; ikhthys = fish)
• Cartilage skeleton
– Bony fishes present in fossil record prior to this lineage splitting off
– Loss of bone derived trait
• Most marine predators
– Teeth derivatives of epidermis (true of all verts)
Hemichordata and Chordata 20
Superclass Gnathostomata Class Chondrichthyes
• Movable jaws
• Rays dorsoventrally flattened
• Spend time on bottom
• Feed on benthic invertebrates
– Teeth designed to crush shells
Hemichordata and Chordata 21
Anatomy of a Female Shark
Hemichordata and Chordata 22
2 dorsal fins caudal fin
2 pelvic fins
2 pectoral fins
lateral line
Spiracle --incurrent flow
Gill slits (5 or 7) --excurrent flow
Superclass Gnathostomata Class Chondrichthyes
• Sharks – General fish-like external
anatomy • Adapted to living in water
• Paired fins provide stability
– Skin with dermal teeth
– Poor eyesight
– Other senses well-developed • Electroreceptors on head
• Lateral line picks up vibrations in water
– Large, oily liver aids buoyancy
– Excrete ammonia
Hemichordata and Chordata 23
Superclass Gnathostomata Class Chondrichthyes
• Sharks
– Teeth develop in whorls and move forward as teeth lost
– Internal fertilization • Oviparous or ovoviviparous
• Males have claspers
– Transfer sperm to female
Hemichordata and Chordata 24
Superclass Gnathostomata Class Osteichthyes
• Bony fish (oste = bone; ichthy = fish)
• Most abundant vertebrates • Freshwater, marine • Bony skeleton
– Elaborate modifications of jaws for different feeding styles
• Gills in common chamber protected by external operculum
• Mucus covering retards bacterial growth and smoothes water flow
• Excrete ammonia
Hemichordata and Chordata 25
Modified by A. Garrison
Superclass Gnathostomata Class Osteichthyes
• Appendages are fins
– Supported by thin bony rays
• Ray-finned fishes
• Most abundant fish group
-OR-
– Supported by internal bony skeleton and muscles
• Fleshy-finned fishes
• Less diverse than ray-finned fishes
• Ancestors of tetrapods
Hemichordata and Chordata 26
Modified by A. Garrison
Superclass Gnathostomata Class Osteichthyes
• Ray-finned fishes
– Very diverse
– Articulated fins • Stability
• Ability to brake and turn
– Scales
– Many with swim bladder • Fill with gas from blood
for buoyancy
– Oviparous or ovoviviparous
Hemichordata and Chordata 27
Superclass Gnathostomata Class Osteichthyes
• Fleshy-finned fishes – Coelacanths marine
– Lungfishes freshwater • Have gills and lungs
– Lungs supplement gills respiration when O2 content low in Australian species
– Lungs collect O2 during dry season, when they are dormant in mucus –lined burrow in dry mud in African and South American species
• Use lobbed fins to move from puddle to puddle
Hemichordata and Chordata 28
Hemichordata and Chordata 29
1 caudal fin
1 or 2 dorsal fins
1 anal fin
2 pectoral fins
operculum
2 pelvic fins
385 MYA—Moving to Dry Land
Advantages
• Plenty of food – Land plants, invertebrates
• Environment rich in oxygen
• Lack of predators
Hurdles • Avoiding desiccation
– Gills – Moist skin – Eggs
• Reproducing without shedding eggs/sperm into water
• Storage of excretory wastes requires non-toxic waste
• Air offers less body support than water
• Sensory structures often collapse out of water
Hemichordata and Chordata 30
Moving to Land—Evolutionary Developments
• To avoid desiccation – Lungs replaced gills
• Don’t collapse or dry out in air
– Tough dry skin replaced moist skin • Skin cells filled with keratin and lipids
– Creates waterproof covering
– Amniotic egg replaced typical aquatic egg and larval development • Membranes protect embryo and allow
gas exchange and excretion of wastes • Shell is porous and allows gas & water
exchange with environment
• To fertilize egg without water, requires internal fertilization (copulation)
Hemichordata and Chordata 31
Moving to Land—Evolutionary Developments
• To avoid toxic wastes issues
– Fish excrete ammonia • Toxic; requires lots of water to
flush from tissues
– Terrestrial vertebrates often excrete uric acid • Less toxic, requires less water to
flush from system
Hemichordata and Chordata 32
Moving to Land—Evolutionary Developments
• To provide more body support
– Stronger vertebral column
– Sturdier girdles
– Rib cage to protect internal organs
• Tetrapod
Hemichordata and Chordata 33
Moving to Land—Evolutionary Developments
• To provide sensory information
– Tympanum picks up vibrations in air
– Stapes transfers vibrations to inner ear
Hemichordata and Chordata; photo by Carl D. Howe; http://commons.wikimedia.org/wiki/File:North-American-bullfrog1.jpg http://creativecommons.org/licenses/by-sa/2.5/deed.en
34
Superclass Gnathostomata Class Amphibia
• Frogs, salamanders, etc. (Amphi = of both kinds; bios = life)
• Tetrapod • Vertebrate characteristics • Adult with lungs • Not free from water
– Moist skin absorbs water when needed
– External fertilization; oviparous • Jelly-coated egg; not amniotic
– Larval development • Tadpole larva w/gills
• Large mouth, small teeth – Swallow prey whole – Nostrils and respiratory tract open
into oral cavity
Hemichordata and Chordata 35
Superclass Gnathostomata Class Amphibia
• Adults carnivorous, juveniles herbivorous
• Circulatory system w/3-chambered heart – 2 atria, 1 ventricle – Mix oxygenated and
deoxygenated blood – OK—ectothermic, so low
energy needs
• Excrete urea (toxic) – Spend time around water
• Cloaca – Empties intestine, reproductive
ducts, excretory bladder
Hemichordata and Chordata 36
Superclass Gnathostomata Class Amphibia
• Order Anura – Frogs, toads
• Order Caudata – Newts, salamanders
• Order Gymnophiona – Caecelians – Tropical – Legless burrowers – Bony scales embedded in
in skin – Internal fertilization – ovoviviparous
Hemichordata and Chordata 37
Phylogeny of Terrestrial Tetrapods (Amniotes)
Hemichordata and Chordata 38
Superclass Gnathostomata Class Reptilia
• Lizards, snakes, turtles, crocidilians (reptil = to crawl)
• Fully terrestrial – Dry skin
• Keratinized scales or dermal bones covered by epidermis
– Internal fertilization • Copulatory organ
– Amniotic egg • Oviparous or ovoviviparous
– Lungs throughout life cycle – Excrete uric acid
• cloaca
• Well-developed teeth – Various types – If venomous, it travels down groove or canal
in fangs
• Imperfect 4-chambered heart – Hole between ventricles – Perfect 4 chambers in crocodilians – Ectothermic
Hemichordata and Chordata 39
Superclass Gnathostomata Class Reptilia
• Order Testudines – Turtles
• Shell of bone covered by keratin
• Vertebrae attached to inside of dorsal shell
• Order Squamata – Lizards and snakes
• Order Crocodilia – Crocodiles and alligators
• Order Aves – Birds—closely related to
Crocodilia—so they are reptiles?
Hemichordata and Chordata 40
?
Superclass Gnathostomata Class Aves
• Birds (aves = bird) • Descendants of bipedal
dinosaurs • Fully terrestrial tetrapods
– Dry skin – Lungs (small) – Scales – Internal fertilization (no
copulatory organ; juxtapose cloaca)
– Amniotic egg – Excrete uric acid
• Cloaca
Hemichordata and Chordata 41
Superclass Gnathostomata Class Aves
• Forelimbs modified as wings
• Scales
• Feathers (= modified scales)
• Well-developed digestive system – Crop for food storage, 2 part
stomach includes gizzard (gravel to grind food)
• 4-chambered heart – Double circuit
– Endothermic • High O2 needs
Hemichordata and Chordata 42
Superclass Gnathostomata Class Aves
• Modifications for flight – Streamlined body shape
– Feathers • Developed from reptilian
scales
– Lightweight • Fewer bones in limbs;
lightweight
• Bone marrow replaced with system of air sacs attached to respiratory system but not used for O2
• No excretory bladder
Hemichordata and Chordata 43
Superclass Gnathostomata Class Aves
• Modifications for flight (cont.) – Bones fused for strength
• Bones of cranium; lumbar vertebrae; pelvic & pectoral girdles to vertebrae;
– Large sternum for attachment of flight muscles
– Wing muscles large, attach to sternum on ventral side of body • Lowers center of gravity • Improves aerodynamics
– Muscles at base of tail control feathers important for flight
Hemichordata and Chordata 44
Superclass Gnathostomata Class Mammalia
• Humans, dogs, cats, rodents, etc (mamm = breat; al = pertaining to)
• Derived from reptilian ancestor (different from birds)
• Fully terrestrial tetrapods – Dry skin – Lungs – Internal fertilization
(copulatory organ) – Amniotic egg – Excrete urea
• different
Hemichordata and Chordata 45
Superclass Gnathostomata Class Mammalia
• Integument with 2 layers – Epidermis and dermis
• Hair or fur – Hair follicle developed
from epidermis
– Sensory whiskers, bristles modified hairs
• Mammary glands – Derived from epidermis
• Movable eyelids
• External ears
Hemichordata and Chordata 46
Superclass Gnathostomata Class Mammalia
• Skeleton
– 7 cervical vertebrae
– Limbs and girdles adapted for lifestyle • Fast runners
– Reduced clavicle and #toes
• Climbers
– Stronger clavicle, limbs elongated
Hemichordata and Chordata 47
Superclass Gnathostomata Class Mammalia
• Teeth and digestive system vary with diet – Herbivores eat lots of cellulose
• No enzymes to break it down • Long digestive tract w/bacteria to
break it down • Inefficient, so eat lots of food
– Insectivores • Eat insects • Digestive system specialized to
break down chitin – Strong gastric enzymes – Stomach lined with tough
epithelium
– Carnivores eat more protein • Easier to digest • Shorter digestive tract • Fewer meals • Premium on intelligence
Hemichordata and Chordata 48
Superclass Gnathostomata Class Mammalia
• Highly developed brain – Convolutions to increase surface
area
• 4-chambered heart – Endothermic
• High O2 needs
• Reproduction – Dioecious – Internal fertilization – 3 types
• Monotremes – Oviparous
• Marsupials – Viviparous; young develop
partially in uterus, then born to grow in pouch attached to teat
• Placentals – Viviparous; young develop fully
in uterus
Hemichordata and Chordata 49
General Vertebrate Pattern
• Ectotherms
– Agnatha
– Chondrichthyes
– Osteichthyes
– Amphiba
– Reptila
• Endotherms
– Aves
– Mammalia
– BUT what about . . .
Hemichordata and Chordata 50
A Very Unusual Vertebrate
• Endothermic mesopelagic fish – Opah (Lampris guttatus) – Produces heat by flapping
pectoral fins – Retains heat using counter-
current heat exchangers in gills • Warm blood from heart runs
alongside cooler blood from gills to heat it before the blood goes to body
– Distributes warm blood to heart and rest of body
Hemichordata and Chordata; photo: NOAA 51